The purpose of this treatment demonstration and research project is to determine the comparative effects of the following three treatment conditions on adolescent drug abusers and addicts in outpatient "drug-free" and residential "drug-free" treatment settings: (1) A "functional-behavioral" type of family therapy approach (Group A), (2) A parent group training intervention method including a structured series of parent group instruction, discussion and counseling sessions, in combination with individual therapy for the adolescent drug abuse client (Group B), (3) The more usual (non-family) treatment plan including individual therapy and peer group therapy for the adolescent clients, but not including any family therapy or parent group sessions (Group C). The project will also determine the client characteristics and the characteristics of his/her family which predict to improvement in drug abuse behavior and other problem behavior, separately from each of the three treatment methods (conditions) to be evaluated.